Hydraulic solenoid valve directly operated with adjustable over-ride speed

ABSTRACT

A hydraulic valve is operated by an electromagnet which is enclosed in a tight chamber and actuates a core movable in a cylinder, said core being provided with longitudinal perforations through which the liquid governed by the valve passes as the core moves through said cylinder; the section of the perforation may be adjustable for regulating the speed of the core in the cylinder.

O United States Patent 1151 3,701,366 Tirelli et al. Oct. 31, 1972 [54] HYDRAULIC SOLENOID VALVE 2,566,774 9/1951 Otis ..251/48 X DIRECTLY OPERATED WITH 2,108,979 2/1938 Wile ..251/50 ADJUSTABLE OVER-RIDE SPEED 2,980,139 4/1961 Lynn ..251/50 X I t I 1 Tim- E50 5 2,923,521 2/1960 Ray ..251/54 [72] nven ors 8: 2: 1 1 1 1x 2,916,019 12/1959 Murphy ..l37/625.65

Italy [73] Assignee: IAlpplzzli'zglcnhiilttllre Oleodma- Primary Examiner-Amold Rosemhal r. 9, t Y Attorney-Diner, Brown, Ramik & 31161: [22] Filed: Aug. 14, 1970 [21] A I. No.: 63 865 pp 57] ABSTRACT 30] Forei Application Priority Data A hydraulic valve is operated by an electromagnet a 893 N70 which is enclosed in a tight chamber and actuates a 11.9291 1970 Italy T core movable in a cylinder, said core being provided 52 U s' (:1. ..137/625.65, 251/50, 251/129, with longitudinal perforations through which he 25 137 liquid governed by the valve passes as the core moves [51] Int. Cl ..F16k 31/06 through said cylinder; the ection of the perforation [58] Field of Search ..251/54, 50, 137, 129, 48; y be j ble f r regulating the speed of the core l37/625.65, 625.64 in the cylinder.

[56] References c1160 10 Claim 4 Drawing Figures UNITED STATES PATENTS 3,441,053 4/1969 Robinson ..251/54 21 PATENIED 3. 701. 366

21 INVENTORS 31 I 1.1 mum sn mzw 30 PADLD "3g a I! 4 $414.) ATTDRNEYS HYDRAULIC SOLENOID VALVE DIRECTLY OPERATED WITH ADJUSTABLE OVER-RIDE SPEED The present discovery concerns electric valves for oleodynamic controls and in particular 3 or 4 way electric valves in which distribution of the oil flow is carried out by a slider which moves linearly in a body (in which the apertures for the oil to pass are open) through the direct action of electromagnets (solenoids) fitted to the said valves.

By oleodynamic (hydraulic and oil) controls, control by any suitable fluid is meant, even other than oil provided that it has certain lubricating properties, and in particular by: non-flammable synthetic fluids (phosphoric esters and/or chlorinated hydrocarbons); synthetic fluids in general, mixtures of water-glycol or water-oil, etc. The speed of movement of the slider bringing about switching of the hydraulic connections of the valve is linked to the speed of movement of the mobile armature of the electromagnet, since at least part of the travel of the mobile armature is carried out with mechanical connection to the slider.

It is important, for purposes of distribution of the hydraulic fluid under pressure, to be able to regulate such speed of switching.

The electrovalves for oleodynamic controls at present on the market consist of a slider (which may be cylindrical, square, etc.) which slides in a body, in which there are the apertures for the oil to pass, and to which the electromagnets are fitted. The anchor of the electromagnet acts on the slider by means of pushers, whole the positioning of the non-excited solenoid is obtained with appropriate springs.

in traditional electric valves with dry electromagnets, the pushers project from the hydraulic casing of the valve through suitable packings.

The main drawbacks of these electric valves consist in the fact that the speed of movement of the mobile armature of the electromagnet and hence of the slider (connected to it) cannot be controlled as it depends on the thrust characteristics of the electric magnet (con stant at equal voltage and frequency of the electric power supply) and on the amount of the resisting forces (forces of inertia, springs, hydraulic resistant forces acting on the slider) and also on variable forces of friction.

Generally the speed of movement is high (depending on the characteristics of response of the electromagnet) and consequently causes a very rapid switching of the hydraulic connections in the valve.

Fast and in any event non-controllable switching is generally associated with phenomena of water-hammer in the pipes and in the valve, with a consequent destructive or in any event harmful effect for the system. 7

Uncontrolled and variable switching times (because of the variable amount of the forces of friction) cause imbalances in the operation of the hydraulic circuit.

The variability of the forces of friction depends on the fact that, since the mechanical connection between the electromagnet anchor and the slider is obtained by means of a pusher on which a hydraulic seal is made by means of packings, such packings, stressed during movement of the pusher, undergo deteriorations due to wear.

The variability of the forces of friction further depends on the fact that the contact surfaces of the magnetic anchor and of the guides are subject to the aggressive action of the atmosphere. Furthermore constant lubrication cannot be obtained and hence during movement of the mobile armature forces of friction are generated due to the sliding of dry metallic surfaces.

The present discovery concerns an electromagnetically controlled hydraulic valve which has the purpose of eliminating the said drawbacks both as regards the variability of the forces of friction and the uncontrollability of the speed with which switching is carried out. The valve in question is for this purpose characterized by the fact that it includes an electromagnet in oil bath, of which the mobile magnetic core in the shape of a piston runs in simple contact in the fixed cylindrical armature and is provided with one or more through holes through which the hydraulic fluid is forced to pass during the stroke, such through holes having a preestablished aperture and means of regulating such aperture being provided.

In this way the mobile core, not being subject to friction of variable amount, but on the contrary being subject only to hydraulic forces of pre-established amount,

is capable of carrying out controlled switching of the valve and hence of the hydraulic connections. In fact in an electric valve, according to the discovery, the switching time depends on the thrust characteristics of the electromagnet (constant at equal voltage and frequency of the electric power supply), on the forces of inertia (constant), on the springs (constant), on the hydraulic resistant forces acting on the slider (constant in constant hydraulic conditions) and on the hydraulic forcesacting on the mobile core (pre-established and constant given parity of through sections of the channels), while it is entirely independent of variable forces of friction.

The main advantages offered by the electric valve which this discovery concerns are linked to the possibility of calibrating the through channels made in the magnetic core by partly blocking them.

In this way it is possible to ensure that the resistant hydraulic forces generated during movement and imposed on the core are adjustable in amount, thus, given equality of other factors conditioning the switching speed, obtaining controlled and preestablished switching times for the hydraulic connections.

This means that the electric valve can be perfectly adjusted to the physical and hydraulic characteristics of the circuit, suppressing or at any rate attenuating phenomena of water hammer in the: pipes and valve.

Other advantages are linked to the cylindrical shape of the mentioned mobile core which, since it runs lubricated along the generating lines of a cylindrical guide chamber, is not appreciably subject to forces of sliding friction, since at the same time the pusher is solid with the mentioned mobile core and not in contact with any fixed part of the electric valve.

In this way the weak forces of friction which are generated are of an amount which does not depend on the life of the electric valve or the environment in which it is installed.

This means that switching times substantially constant in time can be obtained, given equality of the other factors conditioning the switching speed.

For greater clarity a preferred form of construction of the electric valve with mobile magnetic cores in accordance with the discovery will now be described with reference to the attached drawing, in which:

FIG. 1 is a longitudinal section view of an electric valve with l electromagnet, 4 ways, and 2 positions, in which the hydraulic part is shown.

FIG. 2 is a longitudinal section view of an electric valve with 2 electromagnets, 4 ways, and 3 positions, in which the hydraulic part is shown.

FIG. 3 is a longitudinal view of an electric valve with 2 electromagnets, in which the electric and electromagnetic part is shown.

FIG. 4 is a partly sectionised view of the magnetic core with the calibrated channels in accordance with a preferred form.

, With particular reference to FIGS. 1 and 2, such electric valve comprises an alloy cast iron valve 1 in the parallelepiped form of which spaces are obtained by casting of suitable shape to allow the passing of the hydraulic fluid and a slider 29 which, assuming the allowed positions, opens or closes the through apertures and thus allows the oil to flow in the desired directions.

Springs 7-8 act on the slider by means of plates 3 and, if necessary, spacers 5.

Since the plates 3 move against the casing 1 either directly or through spacers 4, the positioning of the slider 29 is ensured with extreme precision and stability.

The casing 1 of the electric valve does not allow leakage of oil since on the one hand the cap 2 is solid with the casing through the screws 13, so that appropriate compression of the seal ring 11 is ensured.

The emergency pusher 6 allows manual positioning of the slider 29 whenever this is required.

The seal ring 9 prevents any leakage of oil along the perimeter of the pusher 6.

On the other hand the seal chamber 20, maintained in position by the flange l2, fastened solidly to the casing by means of the screws 13, compresses the seal ring 10 and at the same time maintains in position the electromagnetic armature 19 which in turn compresses the seal ring 1 1.

Consequently the seal rings 9 and 10, suitably compressed in their housings, prevent leakages of oil through the contact surfaces between the casing 1 and respectively the cap 2 and the parts 12, 19 and 20 of the electromagnet.

With particular reference to FIG. 3, the electromagnet consists mainly of a magnetic part, an electric part, and a mechanical support part. The magnetic structure is in turn composed of the static armature and the mobile armature.

The static armature consists of the magnetic core 19 and the cylinder 20. The two suitably shaped pieces form, from the magnetic point of view, a single whole. The cylinder 20 is sealed against leakages at one end by the pusher 6 and sealing ring 9 and at the opposite end by the seal ring 10.

The mobile armature 17 consists of a suitably shaped core with channels 30 of which the section is preestablished in order to allow the flow of oil from one chamber to the other during movement with a preset speed.

With reference to FIG. 4 a preferred form of construction of such channels 30 is that consisting in axial cylindrical holes with one section of their length threaded in order to allow easy insertion of threaded dowels 31 which are interchangeable and have a calibrated hole.

The copper ring 18 designed for special electrical effects is fastened on the anchor 17, as well as the pusher 16 transmitting the movement between the mobile core 17 and the slider 29 of the electric valve.

On the outside of the seal tube 20 there is a special slot to house the emergency hand pusher 6, on which the packing 9 is fastened in order to ensure a seal to the outside.

The unit consisting of the static armature 19-20 and the packings 10-11 is fastened solidly to the valve casing by the flange 12, fastened to the casing by means of the screws 13.

The spring washer l4 ensures closure of the screws 13.

The electrical unit consisting of the electric winding 24, the insulating support 23, the braiding l5, and the plate 22 is easily fitted on the static armature.

The above-mentioned parts are fastened firmly to each other and thus form a body of hollow cylindrical form, which will be indicated generically as the core 32.

The core 32 is fastened to the magnetic part by locking with the threaded ring nut 21. Adequate compression of the coil in its housing is maintained by interposing the spring washers 25 and 26.

The outside envelope of the coil has a terminal board containing the electrical terminals of the winding, into which terminal board the plug 27 or the plug 28 is inserted with the connections to the general supply network. The plug 27 (or 28) can take 4 different positions in relation to the plan of the terminal board, and hence to the coil, which are determined by means of a screw.

The plug 28 has a bridge rectifier 38 connected to it in order to allow supply of alternating current to the electromagnet, which is structurally designed for direct current supply.

With reference to FIG. 1 and FIG. 2, the movement of the slider 29 and its positioning are obtained by means of the concomitant or independent action of the pusher 16 which is solidly fastened to the anchor of the electromagnet and the springs 7-8.

The slider is kept stably in the extreme rest position (electromagnet not energized) by operation of the spring 8 acting mechanically on the slider 29, through the plate 3 and the spacer 5.

Acquisition and maintenance of the rest position are ensured by the concomitant action of the spring 7 acting in the opposite direction to the slider through the plate and the spacer 4.

When the electromagnet is energized by current being sent to the winding, the mobile core 17 advances and, through the pusher l6, pushes the slider 29, thus promoting opening and closing of the through apertures.

When the core l7-advances it causes a variation in the magnetic field, such as to be accelerated thereby.

At the same time the movement of the core 17 forces oil to pass into the channels 30 (FIG. 4). Such movement of the oil generates a force resisting movement of the core 17 to an extent depending mainly on the form and dimensions of the channels 30 and on the speed of movement of the anchor 17.

During the stage when the slider 29 is advancing, the spring 7 or 8 is loaded and is thus able to bring back the slider to the original position when the action'of the electromagnet ceases.

During the backward movement of the slide 29 under the action of the spring 7 or 8 a similar move- 'ment is imposed on the anchor 17, with the consequent generation of the resistant hydraulic forces already described.

What is claimed is:

1. A hydraulic valve having a direct electromagnetic control device, said hydraulic valve comprising a valve body having a plurality of fluid passages therein including one fluid passage in which hydraulic fluid would normally be present, a valve element positioned within said valve body for shifting movement to control and vary hydraulic fluid flow through said fluid passages, said electromagnetic control device being mounted on said valve body and including a cylinder sealed against external leakage and having an interior in communication with said one fluid passage whereby said cylinder is normally filled with hydraulic fluid from that flowing through said hydraulic valve, said electromagnetic control device also including a winding surrounding said cylinder and a mobile armature slidably mounted within said cylinder for movement under the influence of electrical current flowing in said winding, said armature closely fitting said cylinder and functioning as a piston relative to hydraulic fluid within said cylinder whereby movement of said armature is retarded, and means for operatively connecting said armature to said valve element forshifting the same, said armature having a restricted orifice therethrough for limiting hydraulic fluid flow and thereby slowing and controlling the rate of movement of said armature and said valve element.

2. The hydraulic valve of claim 1 wherein said means connecting said armature to said valve element is a plunger, said plug having a bore aligned with said plunger with said plunger passing through said plug bore, and said plunger having a limited clearance relative to said plug bore with said clearance defining a fluid passage between said chamber and said one valve body passage. a

3. The hydraulic valve of claim 2 wherein said restricted orifice extends axially through said armature and is radially offset from said plug bore.

4. The hydraulic valve of claim 1 wherein the end of said cylinder remote from said valvebody is closed by an end wall having a bore therethrough, a manual plunger slidably mounted in said end wall bore for manually shifting said armature, and means sealing said manual plunger relative to said end wall.

5. The hydraulic valve of claim 1 wherein said winding is carried by a housing telescoped over said cylinder, and means carried by said cylinder releaseably retaining said housing on said cylinder.

6. The hydraulic valve of claim 1 wherein that end of said cylinder opening into said valve body has a fixed plug therein cooperating with said cylinder to define a chamber in wh' h said armatu is o iti e d wherein hydraulic fluid is generally tr psed iiici ep e iidently of hydraulic fluid flowing through said valve body.

7. The hydraulic valve of claim 6 wherein said plug is in the form of a magnetic core.

8. The hydraulic valve of claim 6 wherein said plug is sealed peripherally relative to said cylinder and to said valve body.

9. The hydraulic valve of claim 6 wherein said plug is sealed peripherally relative to said cylinder and to said valve body with said plug having a radial flange clamped between said cylinder and said valve body.

10. The hydraulic valve of claim 6 wherein spring means react against said valve element to position same, and said plug is cup shaped opening towards said valve body and has seated therein one end of a spring element of said spring means. 

1. A hydraulic valve having a direct electromagnetic control device, said hydraulic valve comprising a valve body having a plurality of fluid passages therein including one fluid passage in which hydraulic fluid would normally be present, a valve element positioned within said valve body for shifting movement to control and vary hydraulic fluid flow through said fluid passages, said electromagnetic control device being mounted on said valve body and including a cylinder sealed against external leakage and having an interior in communication with said one fluid passage whereby said cylinder is normally filled with hydraulic fluid from that flowing through said hydraulic valve, said electromagnetic control device also including a winding surrounding said cylinder and a mobile armature slidably mounted within said cylinder for movement under the influence of electrical current flowing in said winding, said armature closely fitting said cylinder and functioning as a piston relative to hydraulic fluid within said cylinder whereby movement of said armature is retarded, and means for operatively connecting said armature to said valve element for shifting the same, said armature having a restricted orifice therethrough for limiting hydraulic fluid flow and thereby slowing and controlling the rate of movement of said armature and said valve element.
 2. The hydraulic valve of claim 1 wherein said means connecting said armature to said valve element is a plunger, said plug having a bore aligned with said plunger with said plunger passing through said plug bore, and said plunger having a limited clearance relative to said plug bore with said clearance defining a fluid passage between said chamber and said one valve body passage.
 3. The hydraulic valve of claim 2 wherein said restricted orifice extends axially through said armature and is radially offset from said plug bore.
 4. The hydraulic valve of claim 1 wherein the end of said cylinder remote from said valve body is closed by an end wall having a bore therethrough, a manual plunger slidably mounted in said end wall bore for manually shifting said armature, and means sealing said manual plunger relative to said end wall.
 5. The hydraulic valve of claim 1 wherein said winding is carried by a housing telescoped over said cylinder, and means carried by said cylinder releaseably retaining said housing on said cylinder.
 6. The hydraulic valve of claim 1 wherein that end of said cylinder opening into said valve body has a fixed plug therein cooperating with said cylinder to define a chamber in which said armature is positioned and wherein hydraulic fluid is generally trapped independently of hydraulic fluid flowing through said valve body.
 7. The hydraulic valve of claim 6 wherein said plug is in the form of a magnetic core.
 8. The hydraulic valve of claim 6 wherein said plug is sealed peripherally relative to said cylinder and to said valve body.
 9. The hydraulic valve of claim 6 wherein said plug is sealed peripherally relative to said cylinder and to said valve body with said plug having a radial flange clamped between said cylinder and said valve body.
 10. The hydraulic valve of claim 6 wherein spring means react against said valve element to position same, and said plug is cup shaped opening towards said valve body and has seated therein one end of a spring element of said spring means. 